A number of systems have been devised for the preparation of numerous types of organophosphorus compounds containing at least one other type of metal. Some of these systems are illustrated in U.S. Pat. Nos. 2,228,659; 2,370,080; 2,488,662; 2,885,417; 3,055,925; 3,065,065; 3,231,347; 3,275,668; 3,297,573; 3,334,978; 3,354,189 and 3,412,182 and United Kingdom Specification No. 1,135,261. These systems generally employ solvents and/or phosphorus compounds containing at least one acidic hydrogen atom.
A system employing triorgano-orthophosphates and anhydrous nickel dichloride is shown in an article by Paul et al. in Indian Journal of Chemistry, 10, (4), pages 447-8, 1972. However, the products of this system are complex crystalline compounds which are insoluble in all the common organic solvents and which are consequently not well suited for olefin polymerization systems. These products apparently crystallize out of the system so that while the anhydrous nickel dichloride starting material is soluble in the triorgano-orthophosphate starting material, there is no evidence that the complex products are soluble even in the triorgano-orthophosphate starting material.
It is a principal object of this invention to provide a novel class of nickel organophosphorus compounds and novel methods of preparing such organophosphorus compounds. It is a further object of this invention to provide a method for preparing nickel organophosphorus compounds soluble in organic solvents from known salts and organic orthophosphates.
Nickel organophosphorus compounds have been used alone and with cocatalysts for the controlled polymerization of olefins as shown, for example, in U.S. Pat. Nos. 3,432,518; 3,655,810 and 3,660,445.
Another object of this invention is to provide new catalyst combinations for controlled oligomerization both alone and during high polymerization of olefins with other catalysts.